Is there a best source model of the Sumatra 2004 earthquake for simulating the consecutive tsunami?

Abstract

International audienceMany studies have attempted to invert the fault source of the Sumatra 2004 event. Whereas they mostly consider the same fault geometry, they lead to a wide range of potential slip distributions. Using tsunami modelling with GEOWAVE, a model based on fully non-linear Boussinesq equations, we investigate the influence of five distinct source models of various origins and the influence of rupture kinematics on the generated tsunami. The simulation results are considered both at ocean-scale and at country-scale. We then compare the results along the Jason-1 track to the corresponding sea surface height anomaly (SSHA) profile, and examine the patterns of maximum sea surface elevation around the Bay of Bengal and on the eastern and southern coastlines of Sri Lanka. In most cases, the synthetic SSHA profiles are not very consistent with the observed one, although they all display a prevailing first wave. The divergence in maximum sea surface elevation appears in particular along the Sri Lankan coast, where three of the models lead to a clearly underestimated tsunami impact. The best models derive from purely seismic and geodetic studies that did not consider any tsunami modelling, thus suggesting that the methods to invert a fault model from tsunami data still need some adjustment, especially concerning the handling of coastal data. In addition, it is important to consider the rupture kinematics along such a long fault, as the generated tsunami is more significant than when considering an instantaneous rupture. In the case of the Sumatra 2004 event, the tsunami impact on Sri Lanka is notably underestimated if modelled without the rupture kinematics. We conclude that for tsunami modelling, a complex description of the fault source model is not absolutely necessary, but some significant parameters such as rupture kinematics should be taken into account

Comparison of Earthquake Source Models for the 2011 Tohoku Event Using Tsunami Simulations and Near-Field Observations

“…10). Although expected, this has not always been the case in previous studies, such as from the 2004 Indian Ocean event, for which seismic and GPS inversions better recreated sea-surface anomalies measured by the Jason-1 satellite than tsunami inversions (Poisson et al, 2011). In the 2011 Tohoku example, tsunami inversions used DART waveforms as input data in their calculations, allowing these sources to better reproduce that same waveform data, in spite of the fact that they used a different tsunami model and often a different method to calculate sea-surface deformation than the methods used in our study.…”

Numerical simulation of tsunami runup in northern Chile based on non-uniform k −2 slip distributions

“…Certainly, our study focuses on numerical simulations of a hypothetical earthquake, and several other factors (not taken into account in this study) may affect the tsunami runup in the near field, which include (1) horizontal displacements of the seabed, (2) high-resolution bathymetry near the shore, (3) the dynamic displacement of the seafloor caused by the space-time rupture process (e.g., Poisson et al 2011). On the other hand, a better resolution of detailed bathymetric charts in the study zone may improve our analysis to regional scale and the computation of runup distributions.…”

“…Recent studies show that a detailed description of the rupture process considering a realistic fault geometry, and/or space-time slip distribution, improves the computed near-field tsunami (e.g., Ide et al 2011;Fujii et al 2011), because these earthquake source effects control part of the strength of the tsunami. For instance, Poisson et al (2011) analyzing some coseismic slip models of the Sumatra 2004, M w 9.1, event, concluded that a complex description of the source model is absolutely necessary for tsunami modeling, but also some physical parameters, such as rupture kinematics, should be taken into account for this event and for long faults.…”

The surge of great earthquakes from 2004 to 2014

“…3), negating any strong segmentation of that part of the plate boundary. Tsunami observations were very limited for the 2004 event, but available data, including sea level altimetry data helped to constrain the rupture length and along-dip slip distribution (e.g., Lay et al, 2005;Fujii and Satake, 2007;Poisson et al, 2011) Less surprising was the regional activation of adjacent great underthrusting ruptures along Sumatra on March 28, 2005 (M w 8.6) (Briggs et al, 2006;Banerjee et al, 2007;Konca et al, 2007) and September 12, 2007 (M w 8.5) (Konca et al, 2008), given the long intervals of strain accumulation since prior failures of the plate boundary in those regions in 1861 and 1833, respectively (Fig. 3).…”